This kind of an electronic circuit module includes a substrate with built-in component, mount components mounted on the substrate with built-in component, a sealing portion covering the mount components, and a shield covering the sealing portion as shown in FIG. 3 in Japanese Patent Application Laid-open No. 2009-004584. In the electronic circuit module, predetermined electronic circuits including built-in components and mount components are three-dimensionally constructed. The shield is connected to ground wiring of the substrate with built-in component, and prevents noises from outside.
In general, the shield in the above-described electronic circuit module is formed of a metal. If the shield is formed of a conductive synthetic resin, the following defects may be induced. In other words, a bonding force between the metal and the synthetic resin tends to be lower than that between the metals or the synthetic resins. If the shield is formed of the conductive synthetic resin, the bonding force between the shield and the ground wiring made of a metal is decreased over time, which induces a local peeling at a boundary. As a result, a conduction property between the shield and the ground wiring is decreased and a desirable shield effect is not easily obtainable.